Speed after adding 3rd log

[ajrunke]

Hi all,

We have a 20ft bennington pontoon with a 60hp merc. I am sourcing a 3rd aluminum log for installation. After talking to a friend, he said the 3rd toon would create drag, lowering our top speed. I've also read the opposite of this using logic like less of the toons are sitting in the water after adding a 3rd toon creating less drag.

The only reason we're adding a 3rd log is for buoyancy. Despite being quite a bit under loaded including equipment and motor, we've submarined (slightly) twice over last last couple years. I don't want people sitting in the front due to this. Since we only have a 60hp, our top speed is 21 light load or 16 fully loaded. With how slow we are, I'd hate to lose a couple mph.

Does anyone have experience with this? Thanks for input!

 

[airshot]

You probably will lose a couple at least, drag and extra weight means slower.

 

[Scott Danforth]

Add lifting strakes

 

[ajrunke]

Add lifting strakes

The tubes we have already have them

This is the response I just received from the tube source:

Hello,

I'm in the market for adding a 3rd tube to our 20ft bennington with a 60hp merc. The main reason is for added buoyancy. Will a 3rd tube lower our already slow top speed because of more drag or should it not affect speed much?

Thanks!

Andrew


Most gain 2-3 mph in speed after adding a third tube. Do you want a center tube or center transom tube?


Logically I agree with airshot's response. I just wish I could find a consensus!

Appreciate everyone's input!

 

[Scott Danforth]

I would get a center transom tube and look for more motor

 

[jlh3rd]

Hi all,

We have a 20ft bennington pontoon with a 60hp merc. I am sourcing a 3rd aluminum log for installation. After talking to a friend, he said the 3rd toon would create drag, lowering our top speed. I've also read the opposite of this using logic like less of the toons are sitting in the water after adding a 3rd toon creating less drag.

The only reason we're adding a 3rd log is for buoyancy. Despite being quite a bit under loaded including equipment and motor, we've submarined (slightly) twice over last last couple years. I don't want people sitting in the front due to this. Since we only have a 60hp, our top speed is 21 light load or 16 fully loaded. With how slow we are, I'd hate to lose a couple mph.

Does anyone have experience with this? Thanks for input!

here's these people....
obviously, biased.....but an option to look at.....
I've considered them myself.....my hesitation is wondering if adding this ..or a third toon....would raise my motor height and cause ventilation issues.....

Fyi...I have a 24','06, twin tube, 25" toons....It had a 60 merc...now has a 115....

 

[ajrunke]

here's these people....
obviously, biased.....but an option to look at.....
I've considered them myself.....my hesitation is wondering if adding this ..or a third toon....would raise my motor height and cause ventilation issues.....

Fyi...I have a 24','06, twin tube, 25" toons....It had a 60 merc...now has a 115....

Thanks, I actually looked at a water glide a year ago but decided against that route. I read too many reviews about it causing bad shaking (probably more to do with the install but still enough for me to shy away from it)

The height of the motor is not something I considered so I appreciate the input. Unfortunately I will now have to do more research to see if this would even work with my motor lol.

 

[jlh3rd]

well....I'm no engineer......
but if you notice on new pontoons that they extend the motor pod back....especially with the tri-toons....
....gotta be a reason for that...and I'm "as-u-ming" that it's because of how toons interfere more so with water to the prop, compared to conventional hulls ....I dunno...
......but I can't take that expensive chance.....

and both my motors were long shafts...and I still had to lower my new motor to reduce ventilation.....which it did dramatically. I was surprised that 11/2, 2 inches can make a big difference....but it did....

 

[Stinnett21]

Not in the know on toons but curious when you add a center log do they attach so well that trailer support is not needed?

 

[ahicks]

My guess for the reasons the newer 'toons use more engine setback are 2. First, today's boat are very often running MUCH heavier motors for the size of the boat being discussed. Second, the swim areas/decks that USED to be forward of the railed area, are now in back of that railed area at the rear of the boat, with many designs using permanently mounted ladders that are MUCH easier to use than the crap we dealt with 20 years ago.

Regarding what to expect when adding a 3rd log, unless this new log has lift strakes, and is possibly a couple inch larger OD, it WILL be just more drag when it comes to speed. It'll float higher, but it's not going to go any faster unless it's lifting the hull up out of the water....

And I would NOT assume any new log you're talking about has lift strakes. That's something I would want to be real clear about when negotiating.....